U.S. patent number 6,042,228 [Application Number 09/071,924] was granted by the patent office on 2000-03-28 for image forming apparatus.
This patent grant is currently assigned to Olympus Optical Co., Ltd.. Invention is credited to Yukitaka Kumagai, Takahisa Yamada.
United States Patent |
6,042,228 |
Yamada , et al. |
March 28, 2000 |
Image forming apparatus
Abstract
An image forming apparatus includes a paper feed station from
which sheets can be fed from a plurality of roll sheets only by
placing the roll sheets in the station, a recording station for
recording desired images on the sheets, and a processing station
for delivering the sheets on which the images are recorded. The
recording station includes a platen roller and a driving pinch
roller for pushing and conveying a fed sheet while the sheet is
drawn by suction by a suction chamber, a carriage unit for
recording an image on the sheet on the suction chamber while moving
along the sheet, and a pair of paper delivery rollers for
delivering the sheet on which the image is recorded. The processing
station includes a table on which the delivered sheets can be
sequentially stacked in a predetermined position, and a biasing
spring for biasing the pivotal distal end portion of the table.
Inventors: |
Yamada; Takahisa (Hachioji,
JP), Kumagai; Yukitaka (Iruma, JP) |
Assignee: |
Olympus Optical Co., Ltd.
(Tokyo, JP)
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Family
ID: |
26442154 |
Appl.
No.: |
09/071,924 |
Filed: |
May 1, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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652926 |
May 24, 1996 |
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Foreign Application Priority Data
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May 31, 1995 [JP] |
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7-133479 |
Apr 23, 1996 [JP] |
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8-101246 |
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Current U.S.
Class: |
347/104; 399/384;
400/578 |
Current CPC
Class: |
B41J
2/01 (20130101); B41J 11/0085 (20130101); B41J
11/06 (20130101); B41J 15/02 (20130101); B41J
15/18 (20130101) |
Current International
Class: |
B41J
11/02 (20060101); B41J 11/06 (20060101); B41J
15/02 (20060101); B41J 11/00 (20060101); B41J
002/01 () |
Field of
Search: |
;347/101,104,16
;399/402,384,385,386,387,389,391 ;271/3 ;400/708,709,579 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Barlow; John
Assistant Examiner: Brooke; Michael S.
Attorney, Agent or Firm: Frishauf, Holtz, Goodman, Langer
& Chick, P.C.
Parent Case Text
This is a continuation of application Ser. No. 08/652,926 filed May
24, 1996.
Claims
What is claimed is:
1. An image forming apparatus comprising first and second sheet
roll holding units which are arranged to simultaneously hold a
plurality of sheet rolls, which sheet rolls are formed by winding a
plurality of sheets having different widths into rolls,
wherein said first sheet roll holding unit rotatably holds a widest
sheet roll of the plurality of sheet rolls, and said second sheet
roll holding unit rotatably holds all others of the plurality of
sheet rolls substantially in series with each other such that the
sheet rolls held by said second sheet roll holding unit are
parallel to the widest sheet roll held by said first sheet roll
holding unit and at least partially overlap with said widest sheet
roll in a sheet widthwise direction.
2. An image forming apparatus according to claim 1, further
comprising:
a plurality of delivery trays for accommodating the sheets on which
images are recorded; and
a processing station having said plurality of delivery trays and
which is horizontally movable with respect to an operation side of
the image forming apparatus.
3. An image forming apparatus according to claim 2, wherein said
plurality of delivery trays are inclined at a predetermined
angle.
4. An image forming apparatus according to claim 2, wherein said
plurality of delivery trays are each respectively provided with a
sheet inlet at one end and with a sheet outlet at another end.
5. An image forming apparatus according to claim 4, wherein said
sheet delivery outlet of each of said plurality of delivery trays
is exposed to the operation side of the apparatus.
6. An image forming apparatus according to claim 2, wherein layouts
of each of said delivery trays in said processing station in a
sheet widthwise direction are set to coincide with layouts of the
sheet rolls held by said first and second sheet roll holding
units.
7. An image forming apparatus according to claim 1, further
comprising a suction chamber having:
a platen board in which a plurality of small holes are formed;
a plurality of suction devices provided in the sheet widthwise
direction of the sheet rolls; and
a separator, provided in accordance with sheet widths of the sheet
rolls held by said second sheet roll holding unit, for separating
respective suction areas of said suction devices.
8. An image forming apparatus according to claim 7, further
comprising selection means for selecting among said respective
suction areas in accordance with sheet widths of the conveyed
sheets.
9. An image forming apparatus according to claim 1, further
comprising:
a recording apparatus; and
a pair of sheet conveyor rollers provided at a downstream side of
said recording apparatus in a sheet conveyance direction,
wherein one of said pair of sheet conveyor rollers, which faces a
sheet recording side, has projections formed on an outer
circumferential surface thereof.
10. An image forming apparatus according to claim 1, further
comprising a suction chamber which has a platen board on which a
plurality of small holes are formed, and at lease one suction
device for sucking conveyed sheets onto said platen board, and
wherein said suction chamber cools a control apparatus having a
control circuit by sucking air.
11. An image forming apparatus according to claim 1, further
comprising:
flanges attached at both ends of said sheet rolls; and
a roller having a groove that is engageable with one of the
flanges.
12. An image forming apparatus according to claim 1, further
comprising:
a recording apparatus; and
a carriage coupled to said recording apparatus for moving said
recording apparatus in the sheet widthwise direction, and
wherein the sheet roll held by said first sheet roll holding unit
is set upward in a space in which said recording apparatus moves in
the sheet widthwise direction.
13. An image forming apparatus according to claim 1, further
comprising:
a platen board in which a plurality of small holes are formed;
a platen roller positioned at an upstream side of the platen board
in a sheet conveyance direction; and
a bend member provided in a conveyance path between said first
sheet roll holding unit and said platen roller, for bending
conveyed sheets in an opposite direction to a direction of curling
of the conveyed sheets.
14. An image forming apparatus according to claim 1, further
comprising:
a suction chamber having a platen board with a plurality of holes
of 1 to 4 mm in diameter; and
a suction device coupled to said suction chamber for sucking
conveyed sheets toward said platen board.
15. An image forming apparatus according to claim 14, wherein said
plurality of holes are more densely provided in side portions of
the platen board than in a center portion of the platen board in
the sheet widthwise direction.
16. An image forming apparatus according to claim 14, wherein said
plurality of holes are more densely provided in a downstream side
of the platen board than in a center portion of the platen board in
the sheet conveyance direction.
17. An image forming apparatus according to claim 1, further
comprising:
a supply apparatus arranged downstream of said second sheet roll
holding unit for simultaneously supplying the plurality of sheets
from sheets held by said second sheet roll holding unit; and
a recording apparatus arranged downstream of said supply apparatus
for recording images on the supplied plurality of sheets, and
wherein said image forming apparatus records images on said
supplied plurality of sheets and simultaneously conveys said
supplied plurality of sheets on which images are recorded while a
carriage finishes one recording operation.
18. An image forming apparatus comprising first and second sheet
roll holding units which are arranged to simultaneously hold a
plurality of sheet rolls, which sheet rolls are formed by winding a
plurality of sheets having different widths into rolls on an upper
surface of said apparatus,
wherein said first sheet roll holding unit rotatably holds a widest
sheet roll of the plurality of sheet rolls, and said second sheet
roll holding unit rotatably holds at least one of the plurality of
sheet rolls such that the sheet roll held by said second sheet roll
holding unit is parallel to the widest sheet roll held by said
first sheet roll holding unit and at least partially overlaps with
said widest sheet roll in a sheet widthwise direction.
19. An image forming apparatus comprising first and second sheet
roll holding units which are arranged to simultaneously hold a
plurality of sheet rolls, which rolls are formed by winding a
plurality of sheets having different widths into rolls, said image
forming apparatus comprising:
recording means for recording images on said sheets;
a conveyor roller arranged downstream of said recording means to
receive sheets from said recording means and to convey the received
sheets on which the images are recorded by said recording means;
and
a table arranged downstream of said conveyor roller to receive and
hold the sheets conveyed by said conveyor roller,
wherein said table includes a plurality of tables having table
widths corresponding to the widths of the sheets of said plurality
of sheet rolls held by said first and second sheet roll holding
units.
20. An image forming apparatus comprising:
a recording apparatus for recording an image on a sheet which is
conveyed from a high-level position to a low-level position;
a conveyor roller for conveying the sheet on which the image is
recorded by said recording apparatus;
a nipping apparatus arranged downstream of said conveyor roller,
said nipping apparatus including:
a nip roller nipping a leading end of the sheet conveyed by said
conveyor roller from the high-level position; and
a table arranged to receive the conveyed sheet nipped by said nip
roller; and
a fan arranged to send air to the sheet which is conveyed from the
high-level position in a suspended state, said fan being situated
between said conveyor roller and said nipping apparatus,
wherein the air from the fan pushes a trailing edge of the sheet
toward an end of the table.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus applied
to, e.g., a printer or a plotter, which is capable of continuously
recording a desired image on sheets of various sizes.
2. Description of the Related Art
Conventionally, the following two methods are known as methods of
forming images on sheets of various sizes (e.g., sheets of A sizes
such as A4, A3, A2, A1, and A0).
The first method is to set only an A0-size sheet roll (which is
formed by winding an A0-size sheet into a roll) in an image forming
apparatus and cut the sheet into a desired size after an image is
formed. The second method is to set a plurality of sheet rolls of
various sizes in an image forming apparatus and cut each sheet into
a desired length after an image is formed.
To form desired images on sheets of various sizes from A4 to A0 by
using these methods, three sheet rolls with different widths are
necessary. More specifically, a 297-mm wide sheet roll corresponds
to A4 and A3 sizes, a 594-mm wide sheet roll corresponds to an A2
size, and a 841-mm wide sheet roll corresponds to A1 and A0 sizes.
Assuming the length of one sheet roll is 150 m, an A0-size sheet
roll generally has a weight of about 10 kg.
To be able to mount these three sheet rolls, in conventional image
forming apparatuses three drawer trays are provided in the lower
portion or on the operation side of an apparatus. Each drawer tray
consists of a holder for holding a sheet roll and a roller for
pulling out a sheet from the sheet roll held by the holder.
In conventional image forming apparatuses of the above sort, a
desired sheet pulled out by the roller is passed through a sheet
path, conveyed to a recording unit by a predetermined conveying
means, and subjected to image recording. The sheet on which an
image is recorded is cut into a predetermined length by a cutting
means arranged downstream in the sheet conveyance direction.
Thereafter, the sheet is rewound and the next image recording
operation is started.
In these conventional image forming apparatuses, however, a large
space is required to arrange the three drawer trays on the
operation side, and a large area on the operation side is occupied
by these drawer trays. As a consequence, it is necessary to arrange
an image-recorded sheet delivery tray on the non-operation side
away from the operation side. This makes operations in one
direction (operation side) of an apparatus difficult.
Also, when a sheet jam occurs in the conventional image forming
apparatuses, it is necessary to pull out the corresponding drawer
tray and this is troublesome for a user. Additionally, the sheet
may be torn off halfway when the user pulls out the drawer tray.
Even when the user can pull out the desired drawer tray, to release
the portion where the sheet is nipped he or she must go around to
the non-operation side of an apparatus and open a sheet jam
management door.
To eliminate these inconveniences, it is possible to equip each
drawer tray with a cutting means. However, this increases the
dimensions and the cost of an apparatus. Furthermore, if all drawer
trays are pulled out, the stability of the apparatus decreases.
To solve these problems, if an apparatus is so designed that all
drawer trays cannot be simultaneously pulled out, the operability
of the apparatus suffers.
In the conventional image forming apparatuses, a heavy sheet roll
is set in the lower drawer tray of an apparatus. This makes the
posture which the user takes when mounting the sheet roll unnatural
and thereby increases the burden of the user when he or she sets
the sheet roll. In addition, the use of drawer trays increases the
sheet conveyance distance to the recording unit, and this increases
the time required for a sheet to reach the recording unit. Also, a
large error appears in the sheet position when the sheet passes
through the recording unit.
In the conventional image forming apparatuses, a sheet detecting
means detects a plurality of portions on the sides of a sheet while
the sheet is slightly moved back and forth, thereby checking
whether the sheet is skewed. However, the moving length of a sheet
in the conveyance direction is very small compared to the width of
the sheet. This makes accurate detection of a skew difficult. In
addition, after the skew detection is performed, a recording means
moves above the sheet to check whether the dimension in the sheet
widthwise direction is appropriate. If the sheet has a slack or the
like, therefore, the recording means may contact and damage the
sheet in some cases.
In conventional image forming apparatuses using an inkjet recording
method, the time required for ink droplets to reach a sheet from a
recording head of a recording means varies if the spacing between
the recording head and the sheet is not maintained constant. Since
a carriage is so controlled as to perform printing while moving, if
this variation occurs the positional accuracy with which ink
droplets adhere to a sheet decreases.
In the conventional image forming apparatuses, recording is done by
using a platen roller or a guide downstream of the platen roller as
a platen surface. If the recording width of a recording means is
large and a high recording speed is necessary, the radius of
curvature of the platen roller cannot be ignored. Accordingly, a
platen roller with a large diameter is necessary, with the result
that a large space is required to accommodate this platen roller
and the size of the apparatus is increased.
When a sheet is supported by the guide downstream of the platen
roller, the sheet may sometimes float from the guide. Also, it is
difficult to maintain the accuracy of the guide constant throughout
the width because of the influence of parts accuracy and thermal
expansion by environments. For example, in a method of conveying a
sheet by drawing the sheet to a belt by suction, it is difficult to
draw the sheet to the belt by suction with no slip because of the
influence of inertia of the sheet or the like. There is another
problem that the conveyance of the belt is not constant due to slip
or the like cause. Furthermore, in a method in which a platen board
is formed by drawing a sheet to a suction box by suction, a load is
applied on the sheet while the sheet is being conveyed and
consequently the sheet sometimes buckles during the conveyance.
When a sheet is also conveyed downstream of the recording unit,
image recording cannot be performed until the sheet reaches a
conveying means on the downstream side, resulting in a low
recording efficiency. Additionally, since a non-recorded portion is
formed on the leading edge of a sheet, the effective recording area
is restricted.
In image forming apparatuses using a method of performing recording
by reciprocating a carriage, if the width of a sheet to be conveyed
is small, the time required for the carriage to return at the side
portion of the sheet becomes longer than an actual recording time.
This makes efficient image recording impossible.
In image forming apparatuses in which recorded sheets are stocked
by sorting them in accordance with their sizes by using a sorter or
the like device, if sheet sizes are large the space occupied by the
sorter itself is increased. This makes the apparatuses of this type
inconvenient in actual use. On the other hand, in apparatuses in
which sheets are stocked by dropping them into a stocker, lower
sheets are smashed to wrinkle by the weights of sheets falling on
them.
Also, coated sheets are primarily used as sheets for an inkjet
method, and these coated sheets easily form paper dust when cut. A
large quantity of dust particles adhere particularly to the cut
surface of a coated sheet or a cutter. Consequently, when the sheet
is cut or when it is rewound or again fed after being cut, dust
particles scatter in an apparatus and adhere to a recording head.
When dust particles thus adhere to the recording head, it is no
longer possible to normally eject ink. This problem of paper dust
is significant in an apparatus having a cutting means above a
recording unit.
Moreover, in the conventional image forming apparatuses, the set
positions of sheet rolls are determined and hence it is not
possible to flexibly change the set positions in accordance with
the use condition or the objective of use. For example, it is
impossible to set only a large-size sheet and record a large image
on the sheet or to change the set position of a small-size sheet
roll to a desired position.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a compact image
forming apparatus capable of stably and efficiently conveying a
sheet with a simple construction and having a high operability.
It is another object of the present invention to provide an image
forming apparatus in which a sheet roll of an arbitrary size can be
set in an arbitrary position in accordance with the use condition
or the objective of use.
Additional objects and advantages of the invention will be set
forth in the description which follows, and in part will be obvious
from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate presently preferred
embodiments of the invention and, together with the general
description given above and the detailed description of the
preferred embodiments given below, serve to explain the principles
of the invention.
FIG. 1 is a schematic view showing the overall construction of an
image forming apparatus according to the first embodiment of the
present invention;
FIG. 2 is a perspective view showing a state in which first to
third roll sheets are set in a paper feed station;
FIGS. 3A to 3C are plan views showing variations of the roll sheets
set in the paper feed station;
FIG. 4 is a partial sectional view showing a state in which the
first roll sheet is set on a first paper feed roller;
FIG. 5 is an exploded perspective view showing the construction of
a suction chamber provided in a recording station;
FIG. 6 is a view for explaining an operation of simultaneously
recording images on a plurality of roll sheets;
FIG. 7 is a view showing a state in which a carriage unit is placed
in its home position;
FIG. 8 is a perspective view schematically showing the construction
of a position detection circuit of the carriage unit;
FIG. 9 is a view for explaining an operation when a sheet posture
is measured by a sensor of the carriage unit;
FIGS. 10A to 10E are views showing the steps of paper delivery
processing in a processing station;
FIG. 11 is a side view showing the construction of the processing
station according to a modification;
FIG. 12 is a perspective view of the processing station in FIG.
11;
FIG. 13 is a sectional view showing the internal constructions of
the paper feed station and the recording station;
FIG. 14 is a sectional view showing the construction of a portion
in which the paper feed station and the recording station
joins;
FIG. 15 is a partial sectional view showing a state in which a top
cover and a front cover are opened to expose the interior;
FIG. 16 is a partial sectional view showing a state in which one
end of a guide bar arranged near the joint portion is connected to
a lever via a link mechanism;
FIG. 17 is a side view of the construction shown in FIG. 16, in
which a driving pinch roller is brought into contact with or
separated from a platen roller by a lever operation;
FIG. 18A is a sectional view showing a state in which the driving
pinch roller is in contact with the platen roller;
FIG. 18B is a sectional view showing a state in which the driving
pinch roller is separated from the platen roller;
FIG. 19 is a partial perspective view showing the positional
relationship between nip rollers, a table, and a stopper provided
in the processing station;
FIG. 20 is a plan view showing the construction of a paper feed
station provided in an image recording apparatus according to the
second embodiment of the present invention;
FIG. 21 is a perspective view showing a state in which roll sheets
of different sizes are set in the paper feed station in FIG.
20;
FIG. 22 is a view showing a state in which sheets of different
sizes are fed from the paper feed station to a recording
station;
FIG. 23A is a view of the construction of a coupling mechanism
applied to the image recording apparatus of the present invention,
showing a state in which a plurality of paper feed rollers are
simultaneously rotated;
FIG. 23B is a view of the construction of the coupling mechanism
applied to the image recording apparatus of the present invention,
showing a state in which the paper feed rollers are independently
rotated;
FIG. 24 is a perspective view showing the construction of a support
roller mechanism arranged on the front and rear sides of the image
recording apparatus of the present invention;
FIG. 25A is a perspective view showing the arrangement of a
plurality of pinch rollers applied to the image recording apparatus
of the present invention, in which a plurality of pinch rollers
arranged on the front side are illustrated;
FIG. 25B is a perspective view showing the arrangement of a
plurality of pinch rollers applied to the image recording apparatus
of the present invention, in which a plurality of pinch rollers
arranged on the rear side are illustrated;
FIG. 26 is a view showing the construction of a conveyance path and
its peripheral portion between the paper feed station and the
recording station;
FIG. 27A is a view of the construction of a conveyance guide
provided in the conveyance path, showing a state in which the
conveyance guide is arranged on the conveyance path;
FIG. 27B is a view of the construction of the conveyance guide
provided in the conveyance path, showing a state in which the
conveyance guide is retracted from the conveyance path;
FIGS. 28A to 28C are plan views showing states in which roll sheets
of different sizes are set in the paper feed station;
FIG. 29 is a perspective view showing the outer appearance of an
overall image forming apparatus according to one embodiment of the
present invention;
FIG. 30 is a diagram showing a sheet in the waiting position;
and
FIG. 31 is a diagram showing the sheet in another position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An image forming apparatus according to the first embodiment of the
present invention will be described below with reference to the
accompanying drawings. Note that the image forming apparatus of
this embodiment is so designed as to be able to record a desired
image on a sheet of a predetermined size, and it is possible to
use, e.g., recording paper, a sheet of paper, a plastic film, or
cloth as the sheet.
The embodiment will be described below by taking an image forming
apparatus using a sheet of paper as an image recording sheet as an
example.
As shown in FIG. 1, the image forming apparatus of this embodiment
includes a paper feed station 1, a recording station 2, and a
processing station 3. The paper feed station 1 can accommodate a
plurality of roll sheets each formed by winding a sheet of a
predetermined size into a roll (although only two roll sheets 101
and 102 are shown in FIG. 1, this embodiment uses first, second,
and third roll sheets 101, 102, and 103 as shown in FIG. 2). The
recording station 2 records a desired image on the sheet (101, 102,
or 103) fed from the paper feed station 1. The processing station 3
delivers the sheet on which the image is recorded by the recording
station 2.
In this embodiment, the first roll sheet 101 is formed by winding a
841-mm wide sheet into a roll, the second roll sheet 102 is formed
by winding a 594-mm wide sheet 102 into a roll, and the third roll
sheet 103 is formed by winding a 297-mm wide sheet 103 into a
roll.
The recording station 2 includes a platen unit 5 and a carriage
unit 4. The platen unit 5 is so arranged as to extend in a
direction perpendicular to a sheet conveyance direction T. The
carriage unit 4 records a desired image on a sheet while moving
along the platen unit 5.
As shown in FIG. 5, a platen roller 501 is arranged in the
direction perpendicular to the sheet conveyance direction T in the
platen unit 5 of the recording station 2. This platen roller 501 is
rotatably supported by first and second aluminum frames 201 and 202
that oppose each other.
The first and second frames 201 and 202 have positioning notches
formed on the upstream and downstream sides in the sheet conveyance
direction T. Aluminum upstream and downstream stays 505 and 506
given a high straightness by a milling cutter or a wire cutter are
fixed to these positioning notches.
A plurality of aluminum platen boards 502 are fixed to the end
faces of these upstream and downstream stays 505 and 506 on an
operation side Z to extend in the direction perpendicular to the
sheet conveyance direction T. Windows 502a for the platen roller
501 and air suction holes 502b (about 2 mm in diameter) are formed
in each platen board 502. Since these platen boards 502 are fixed
to the upstream and downstream stays 505 and 506, a high flatness
is realized and maintained in the sheet conveyance direction T.
The use of the platen boards 502 can achieve a higher flatness than
when a single large platen board is used, and also makes the
problem of "warp" difficult to arise.
The platen roller 501 used in this embodiment is a stepped roller.
When the platen boards 502 are fixed to the end faces of the
upstream and downstream stays 505 and 506 on the operation side Z,
the largest outer circumferential portions of the platen roller 501
are exposed from the windows 502a in the platen boards 502. Note
that the maximum diameter surface of the platen roller 501 is
nearly flush with the surface of the platen board 502 on the
operation side Z (i.e., the surface opposing the carriage unit 4)
due to the parts accuracies of the first and second frames 201 and
202, the upstream and downstream stays 505 and 506, the platen
roller 501, and the platen boards 502.
A cover 503 is attached to the upstream and downstream stays 505
and 506 to oppose the platen boards 502. A plurality of suction
means 504 are arranged on the inner surface of the cover 503 (i.e.,
the surface opposing the platen boards 502).
In the platen unit 5 with the above construction, the platen boards
502, the first and second frames 201 and 202, the upstream and
downstream stays 505 and 506, and the cover 503 constitute a
suction chamber.
As shown in FIG. 1, the paper feed station 1 is arranged above the
recording station 2. As illustrated in FIG. 2, this paper feed
station 1 is so designed as to be able to mount the first, second,
and third roll sheets 101, 102, and 103.
More specifically, as illustrated in FIGS. 1, 2, and 4, the first
roll sheet 101 is rotatably supported on a first stainless steel
paper feed roller 104 and a first stainless steel support roller
110 arranged at a predetermined interval between the first and
second frames 201 and 202 (FIG. 4).
The first paper feed roller 104 includes paper feed roller shafts
104a extending from its two ends. These paper feed roller shafts
104a are rotatably supported by the first and second frames 201 and
202 via bearings 104b. Also, sleeves 113 are fitted on the paper
feed roller shafts 104a, and the fitting portions have a low
friction coefficient.
The first support roller 110 (FIG. 2) has shafts (not shown)
protruding from its two ends and is rotatably supported by the
first and second frames 201 and 202 via these shafts. Sleeves (not
shown) are rotatably fitted on the shafts.
Flanges 101a and 101b are detachably attached to the two ends of
the first roll sheet 101. The first roll sheet 101 is rotatably
supported on the first paper feed roller 104 and the first support
roller 110 by placing these flanges 101a and 101b on the sleeves
113 and 114 of the first paper feed roller 104 and on the sleeves
of the first support roller 110.
The sleeve 113 of the first paper feed roller 104 rotatably holds
the flange 101a of the first roll sheet 101 and positions the first
roll sheet 101 in the widthwise direction. The other sleeve 113
rotatably holds the flange 101b, and the two sleeves of the first
support roller 110 rotatably hold the flanges 101a and 101b. To
allow smooth sheet conveyance, the outer diameter of each sleeve is
made smaller than the outer diameter of the central portion of the
first paper feed roller 104.
A pinch roller 107 for nipping the sheet 101 is separably urged
against the central portion of the first paper feed roller 104. The
first paper feed roller 104 is so treated as to have a high
friction coefficient at least on the circumferential surface in
this central portion. As this treatment method, it is possible to
press rubber into the roller or coat the roller with an aluminum
powder. However, a roller which does not easily bend is necessary
when the wide sheet 101 is conveyed as in this embodiment. In the
method of pressing rubber into the roller, the strength of the
roller decreases because the diameter of the roller is reduced by
the thickness of the rubber. Therefore, a method in which the
roller is coated with an aluminum powder to a thickness of about
150 fm or less is preferred.
A driving belt 116 for transmitting a driving force from a motor
117 arranged outside the first frame 201 is hooked on the paper
feed roller shaft 104a of the first paper feed roller 104. The
first paper feed roller 104 is rotated in a predetermined direction
via a clutch 115. The motor 117 is so designed as to rotate the
platen roller 501 in the forward and reverse directions via a worm
mechanism. The driving force from the motor 117 is not transmitted
to the first support roller 110; that is, the first support roller
110 rotates when the flanges 101a and 101b of the first roll sheet
101 rotate.
As illustrated in FIG. 2, the second and third roll sheets 102 and
103 can be mounted parallel to the first roll sheet 101. More
specifically, the second roll sheet 102 is rotatably supported on a
second paper feed roller 105 and a second support roller 112 (FIG.
1), and the third roll sheet 103 is rotatably supported on a third
paper feed roller 106 and a third support roller 111. Pinch rollers
108 and 109 are separably urged against the central portions of the
second and third paper feed rollers 105 and 106, respectively.
Accordingly, the second and third paper feed rollers 105 and 106
are so treated as to increase the friction coefficient at least in
these central portions. Note that the constructions of the second
and third paper feed rollers 105 and 106 and the second and third
support rollers 112 and 111 are identical with those of the first
paper feed roller 104 and the first support roller 110, and so
drawings and descriptions thereof will be omitted.
As illustrated in FIG. 4, the driving force transmitted from the
motor 117 to the driving belt 116 via the worm mechanism is
selectively transmitted to the second and third paper feed rollers
105 and 106 via the clutch 115. Consequently, the first, second,
and third paper feed rollers 104, 105, and 106 can be independently
rotated as they are selectively driven by the clutch 115.
The arrow Z shown in FIGS. 1 and 2 indicates the operation side.
The first, second, and third paper feed rollers 104, 105, and 106
used in this embodiment are so arranged that the widest and
heaviest first roll sheet 101 is positioned close to the operation
side Z and the second and third roll sheets 102 and 103 are
positioned at the back of the first roll sheet 101. The second and
third roll sheets 102 and 103 are arranged parallel to the first
roll sheet 101 such that a spacing with which they do not overlap
each other in the widthwise direction is kept between them. The
first roll sheet 101 overlaps the second and third roll sheets 102
and 103 in the widthwise direction.
FIGS. 3A and 3B illustrate variations of the arrangement, viewed
from the above, of the first, second, and third roll sheets 101,
102, and 103 used in this embodiment. As in FIGS. 3A and 3B, the
second and third roll sheets 102 and 103 with small widths are
arranged parallel to the first roll sheet 101 with the largest
width such that they do not overlap each other in the widthwise
direction. This makes it possible to arrange a plurality of roll
sheets at the same time in a small space. FIG. 3C shows a variation
in which a fourth roll sheet 103' is arranged in addition to the
first, second, and third roll sheets 101, 102, and 103.
A construction for conveying the sheets 101, 102, and 103 from the
first, second, and third roll sheets 101, 102, and 103 to the
recording station 2 will be described below with reference to FIGS.
13 and 14.
As shown in FIGS. 13 and 14, the pinch rollers 107, 108, and 109
urged against the first, second, and third paper feed rollers 104,
105, and 106 are rotatably held in brackets 118a, 119a, and 120a
attached to the rocking distal end portions of rockingly supported
first, second, and third movable guides 118, 119, and 120,
respectively.
The first, second, and third movable guides 118, 119, and 120 are
supported to be rockable in directions perpendicular to the axial
directions of the first, second, and third paper feed rollers 104,
105, and 106, respectively, and always biased against their own
weights to the fist, second, and third paper feed rollers 104, 105,
and 106 by biasing springs 118b, 119b, and 120b arranged near the
brackets 118a, 119a, and 120a, respectively. As a consequence, the
pinch rollers 107, 108, and 109 are tightly urged against the outer
circumferential surfaces of the first, second, and third paper feed
rollers 104, 105, and 106, respectively.
With the pinch rollers 107, 108, and 109 being tightly urged
against the outer circumferential surfaces of the first, second,
and third paper feed rollers 104, 105, and 106, respectively, the
first movable guide 118 opposes a first fixed guide 122 fixed to
the first and second frames 201 and 202 and thereby forms a first
conveyance path (FIG. 4). The second movable guide 119 opposes a
second fixed guide 121 fixed to the first and second frames 201 and
202 and thereby forms a second conveyance path. The third movable
guide 120 (FIG. 14) opposes the second fixed guide 121 to form a
third conveyance path.
The first to third conveyance paths thus formed join at the
position of a guide bar 208 held by the first and second frames 201
and 202.
A plurality of pinch holders 209 being rotatable only a
predetermined angle are held at predetermined intervals by the
guide bar 208. A driving pinch roller 507 (FIG. 14) is rotatably
supported by the distal end portion of each pinch holder 209. More
specifically, as shown in FIGS. 16 to 18B, each pinch holder 209 is
fastened to the guide bar 208 via a metal piece 213. One end
portion of the metal piece 213 is inserted into a hole 209a (FIGS.
17, 18A, and 18B) of the pinch holder 209 formed on the side away
from each sheet conveyance path. The central portion of the metal
piece 213 is fastened to the guide bar 208 by a machine screw 701
(FIGS. 16, 18A, and 18B). One end of each metal piece 213 biases
and supports a spring 214 accommodated in the hole 209a of the
pinch holder 209, and the other end of the metal piece 213
regulates the range of rotation of the pinch holder 209. Since the
movement in the axial direction of each pinch holder 209 is
regulated by the metal piece 213, these pinch holders 209 do not
move in the axial direction of the guide bar 208.
The guide bar 208 to which the pinch holders 209 are thus attached
is connected to a lever 212 via a link mechanism 211 arranged
outside the first frame 201.
As illustrated in FIG. 17, therefore, when the lever 212 is pivoted
in directions indicated by the arrows, the driving pinch roller 507
of each pinch holder 209 can be brought into contact with and
separated from the platen roller 501.
More specifically, when the lever 212 is pivoted from a state
indicated by the alternate long and two dashed lines to a state
indicated by the solid lines in FIG. 17, the guide bar 208 is
slightly rotated via the link mechanism 211. When the guide bar 208
thus rotates, each metal piece 213 also rotates and the biasing
force of the spring 214 acts on the pinch holder 209. Since each
pinch holder 209 is biased toward the platen roller 501 by the
biasing force of the spring 214, the driving pinch roller 507
attached to the pinch holder 209 is pressed against the platen
roller 501 (FIG. 18A). When the lever 212 is pivoted in the reverse
direction, the pinch holders 209 are moved apart from the platen
roller 501. Consequently, each driving pinch roller 507 is
separated from the platen roller 501 (FIG. 18B).
As shown in FIG. 16, sleeves 210 are rotatably fitted between the
pinch holders 209 on the guide bar 208. The outer circumferential
surface of each sleeve 210 is in almost the same position as a
partial arcuated portion 209b (FIGS. 17, 18A, and 18B) of the outer
circumferential surface, on the sheet conveyance path side, of each
pinch holder 209. In the other portion, the outer circumferential
surface of the sleeve 210 slightly projects from the outer
circumferential surface of the pinch holder 209 in order that the
sheets 101, 102, and 103 positively come in contact with each
sleeve 210.
In this construction, each pinch holder 209 functions as a sheet
guiding means which, by using the arcuated portion 209b, bends and
guides the sheet 101, 102, or 103 conveyed through the first,
second, or third conveyance path. The pinch holder 209 also
functions as a means for bringing the driving pinch roller 507 into
contact with the platen roller 501 or separating the driving pinch
roller 507 from the platen roller 501. Consequently, it is possible
to minimize the path lengths from the first, second, and third
paper feed rollers 104, 105, and 106 to the platen roller 501.
In this embodiment, the first, second, and third paper feed rollers
104, 105, and 106 are arranged closer to the operation side Z than
the conveyance path joint position (i.e., the platen board 502)
near the arcuated portion 209b of each pinch holder 209. The first,
second, and third roll sheets 101, 102, and 103 are entirely
arranged on the operation side Z. In particular, the first roll
sheet 101 is set above the moving space of the carriage unit 4. As
a result, a large moving space can be ensured for the carriage unit
4 in the recording station 2 without changing the size of the
entire apparatus, i.e., the area of the floor occupied by the
apparatus. Additionally, since the first, second, and third roll
sheets 101, 102, and 103 are entirely arranged on the operation
side 2, the user can readily set the first, second, and third roll
sheets 101, 102, and 103. This improves the operability of the
apparatus.
As illustrated in FIG. 14, a thin plate member 207 is provided in
the conveyance path joint position in order that the sheet 101,
102, or 103 conveyed through the first, second, or third conveyance
path is bent and smoothly guided by the arcuated portions 209b.
This thin plate member 207 bends the leading edge of primarily the
sheet 101, conveyed from the first conveyance path, in a direction
opposite to the direction of curling. The thin plate member 207 is
made of a stainless steel plate about 0.5 mm in thickness and has a
fulcrum in a position closer to the operation side Z. The thin
plate member 207 is so designed as to contact the pinch holders 209
and the sleeves 210 by its own weight. Note that the distal end
portion of the thin plate member 207 on the side away from the
fulcrum is partially bent toward the sleeves 210 and extends to the
vicinity of the conveyance path joint position.
In the above construction for guiding and conveying the sheets 101,
102, and 103 from the first, second, and third roll sheets 101,
102, and 103 to the recording station 2, the first movable guide
118 is pushed down against the biasing force of the biasing spring
118b, and the leading edge of the first roll sheet 101 is inserted
and nipped between the first paper feed roller 104 and the pinch
roller 107. The rotational driving force of the platen roller 501
which is rotated by the motor 117 is transmitted to the first paper
feed roller 104 via the driving belt 116 and the clutch 115,
rotating the first paper feed roller 104 in the forward direction.
Consequently, the sheet 101 is conveyed through the first
conveyance path formed by the first movable guide 118 and the first
fixed guide 122.
Thereafter, the leading edge of the sheet 101 conveyed to the
conveyance path joint position near the pinch holders 209 is guided
while being pressed down by the thin plate member 207 sitting on
the sleeves 210 by its own weight. Since the thin plate member 207
has a proper weight, the sheet 101 moves forward along the thin
plate member 207 without being buckled or pushing the thin plate
member 207 upward. Additionally, the sheet 101 is smoothly conveyed
on the sleeves 210 because the sleeves 210 are rotatably fitted on
the guide bar 208.
The leading edge of the sheet 101 is then bent between the second
fixed guide 121 and the sleeves 210 and guided to between the
platen boards 502 and the pinch holders 209. The leading edge of
the sheet 101 is nipped between the platen roller 501 and the
driving pinch rollers 507 and conveyed to an image recording area
to be described later.
Similarly, the leading edge of the second roll sheet 102 can be
nipped between the second paper feed roller 105 and the pinch
roller 108 by pushing down the second movable guide 119 against the
biasing force of the biasing spring 119b. The sheet 102 is conveyed
through the second conveyance path formed by the second movable
guide 119 and the second fixed guide 121 by transmitting the
rotational driving force of the platen roller 501 to the second
paper feed roller 105 via the clutch 115. The leading edge of the
sheet 102 is bent between the second fixed guide 121 and the
sleeves 210 and guided to between the platen boards 502 and the
pinch holders 209. The leading edge of the sheet 102 is nipped
between the platen roller 501 and the driving pinch rollers 507 and
conveyed to the image recording area to be described later.
As illustrated in FIG. 14, the leading edge of the third roll sheet
103 also can be nipped between the third paper feed roller 106 and
the pinch roller 109 by pushing down the third movable guide 120
against the biasing force of the biasing spring 120b. The sheet 103
is conveyed through the third conveyance path formed by the third
movable guide 120 and the second fixed guide 121 by transmitting
the rotational driving force of the platen roller 501 to the third
paper feed roller 106 via the clutch 115. The leading edge of the
sheet 103 is bent between the second fixed guide 121 and the
sleeves 210 and guided to between the platen boards 502 and the
pinch holders 209. The leading edge of the sheet 103 is nipped
between the platen roller 501 and the driving pinch rollers 507 and
conveyed to the image recording area to be described later.
As shown in FIG. 13, in the image recording area provided in the
recording station 2, the suction chamber of the platen unit 5 is
evacuated to a negative pressure by the suction means 504 (FIG. 5).
Accordingly, the air is drawn into the chamber by suction through
the large number of holes 502b (FIG. 5) formed in the platen boards
502.
These holes 502b are formed downstream, in the sheet conveyance
direction T (FIG. 5), of the windows 502a (FIG. 5) through which
the platen roller 501 and the driving pinch roller 507 are
nipped.
The sheet (101, 102, or 103) pushed out by the platen roller 501
and the driving pinch rollers 507 is kept flat while being drawn to
the platen boards 502 by suction and slides on the platen boards
502 as it is pushed.
Note that the sheet sliding surface (on which the sheet slides) of
each aluminum platen board 502 is treated with alumite in order to
decrease the friction coefficient.
In accordance with the relationship between the direction of
curling of the sheet 101, 102, or 103 and the positions of the
platen boards 502, the leading edge of the sheet comes in contact
with the platen boards 502, and the central swelled portion of the
sheet formed by curling in the direction of the operation side Z
separates from the platen boards 502.
Since the air in the central swelled portion of the sheet 101, 102,
or 103 conveyed in this state is drawn by the suction means 504 by
suction, the sheet 101, 102, or 103 is brought into tight contact
with the platen boards 502.
The holes 502b in the platen boards 502 can be formed to have a
diameter of approximately 1 to 4 mm. According to the experiments,
diameters of about 2 mm were appropriate because the amount of
deformation of a sheet was small. The holes 502b are densely formed
near the side portions in the widthwise direction of a sheet and on
the downstream side of each platen board 502 and sparsely formed in
other portions.
The formation of these holes 502b enhances the effect of bringing
the side portions of a sheet, which tend to float from the platen
boards 502, into tight contact with the platen boards 502. This
also enhances the effect of pressing down the sheet 101, 102, or
103 tightly on the upstream side of a cutter 205 to be described
later when the sheet is cut by the cutter 205.
As illustrated in FIG. 13, the cutter 205 is attached to the
downstream stay 506 (FIG. 5) constituting the suction chamber. The
cutter 205 consists of a fixed blade 205a extending in the sheet
widthwise direction (the direction perpendicular to the sheet
conveyance direction) and a movable blade 205b which moves along
the fixed blade 205a and cuts the sheet 101, 102, or 103.
A pair of paper delivery rollers 206 rotatably pressed against each
other are arranged downstream of the cutter 205. The paper delivery
rollers 206 are a driving roller 206a to be pressed against the
non-recorded surface of a sheet and a driven roller 206b to be
pressed against the recorded surface of a sheet. This driven roller
206b is so arranged as to be pressed against the recorded surface
of a sheet before ink dries. To prevent ink from adhering to the
outer circumferential surface of the driven roller 206b, therefore,
needle-like projections (not shown) having acute points are formed
on the outer circumferential surface of the driven roller 206b.
In this construction, when the sheet 101, 102, or 103 is cut by the
cutter 205, a portion of the sheet upstream of the cut portion is
drawn by suction and held to the platen boards 502 by the suction
force of the suction chamber as described above, and a downstream
portion of the sheet is pinched between the paper delivery rollers
206. This prevents any shift of the sheet when the sheet is cut.
Furthermore, since the cutter 205 is directly attached to the
suction chamber, the suction chamber can be positioned near the cut
portion. Consequently, the cut portion of the sheet positioned and
held on the suction chamber can be cut with a high accuracy.
Also, as illustrated in FIG. 5, the interior of the suction chamber
is separated in at least one position in the sheet widthwise
direction by a separator 508 having a notch for receiving the
platen roller 501. Note that suction by the suction means 504 acts
in each region separated by the separator 508. In this embodiment,
the separator 508 is arranged in the boundary between the second
roll sheet 102 and the third roll sheet 103. Two suction means 504
are provided in a region for the second roll sheet 102, and one
suction means 504 is provided in a region for the third roll sheet
103.
In this construction, when the first roll sheet 101 having the
largest width is conveyed a total of three suction means 504 are
simultaneously operated. On the other hand, when the third roll
sheet 103 having the smallest width is conveyed only one suction
means 504 arranged in the region separated by the separator 508 is
operated. When the second roll sheet 102 is conveyed the other two
suction means 504 are operated.
The use of the separator 508 makes it possible to prevent the
suction force of the suction chamber from becoming nonuniform
depending on the width of a sheet being conveyed and to consume
only necessary power. Additionally, since only necessary suction
means 504 are thus selectively operated, generation of noise can be
minimized.
The carriage unit 4 provided in the recording station 2 will be
described below with reference to FIGS. 1 to 13.
The carriage unit 4 can move in opposition to and along the platen
boards 502 of the platen unit 5 (FIG. 2). For this purpose,
openings 201a and 202a which allow the passage of the carriage unit
4 are formed to oppose each other in the first and second frames
201 and 202, respectively (FIG. 5).
Two linear guides 203 and 204 are provided in positions adjacent to
the openings 201a and 202a and in the vicinity of the platen unit 5
to extend in the direction perpendicular to the sheet conveyance
direction T. These linear guides 203 and 204 are parallel to each
other along the sheet conveyance direction T and extend parallel to
the platen boards 502.
The linear guides 203 and 204 are fixed to the first and second
frames 201 and 202 such that the two end portions of each linear
guide project outward from the first and second frames 201 and
202.
The carriage unit 4 is slidably held by the two linear guides 203
and 204 via bearings. In a standby state before the apparatus is
operated, the carriage unit 4 is placed in a home position (FIG. 7)
outside the first frame 201.
An image recording unit 401 for ejecting ink components of four
colors is provided in the carriage unit 4. In this image recording
unit 401, four recording heads each having a plurality of nozzles
(not shown) capable of ejecting ink are arranged along the sheet
conveyance direction T. More specifically, the image recording unit
401 is constituted by arranging a recording head K for ejecting
black ink, a recording head C for ejecting cyan ink, a recording
head M for ejecting magenta ink, and a recording head Y for
ejecting yellow ink, in this order from the upstream side in the
sheet conveyance direction T.
These recording heads are so arranged that their respective ink
components do not overlap each other in the slide direction of the
carriage unit 4 (i.e., the direction perpendicular to the sheet
conveyance direction T). Also, each recording head is so positioned
as to maintain a fixed distance (about 1 mm) from the platen boards
502 while the carriage unit 4 is sliding. These recording heads
used in this embodiment are inkjet heads, and the number of
nozzles, i.e., channels, is 256 for each ink component.
The nozzles of these recording heads are so formed that the
intervals between them are, e.g., 360 (DPI) along the sheet
conveyance direction T. In this case the recording width of ink of
one color is about 18 mm. The recording heads used in this
embodiment are arranged at a pitch which is five-fourths of the
width of each recording head. Accordingly, the width of the image
recording unit 401 is about 90 mm. As a result, the platen boards
502 used in this embodiment are flatly positioned so that the
distance to each recording head is kept constant throughout at
least the width of the image recording region 402.
The carriage unit 4 includes ink cartridges 4a containing ink
components of different colors and ink tanks 4b. The ink contained
in each ink cartridge 4a is supplied to the corresponding recording
head through the corresponding ink tank 4b.
In the carriage unit 4, a sensor S4 for detecting the sheet 101,
102, or 103 is arranged to oppose the platen boards 502.
As illustrated particularly in FIG. 7, the sensor S4 is arranged in
a position upstream of the image recording unit 401 in the sheet
conveyance direction T and closest to the sheet, when the carriage
unit 4 is placed in the home position.
A position detection method of the carriage unit 4 will be
described below.
Assume that, as shown in FIG. 8, the carriage unit 4 is placed in
the home position (FIG. 7) outside the first frame 201. When a
driving mechanism (not shown) is operated in this state, the
carriage unit 4 reciprocates along the platen boards 502 in
directions indicated by the arrows in FIG. 8 while being guided by
the linear guides 203 and 204.
The carriage unit 4 has a rear sensor 404 which can read the scale
values (not shown) of a linear scale 405 extended over a width
larger than the range of the reciprocating motion. Note that the
scale values are recorded on the linear scale 405 at, e.g.,
intervals meeting the recording density of each recording head.
The pulse signal read by the linear sensor 404 is applied to an
encoder pulse counter 407 via a control circuit (CPU) 406, and the
pulse outputs are counted. In the home position (FIG. 7) described
above, a home position sensor 408 connected to the control circuit
406 is provided and detects whether the carriage unit 4 is in the
home position.
On the basis of the output from the home position sensor 408, the
control circuit 406 counts the pulse outputs from the encoder pulse
counter 407 and thereby detects the current position of the
carriage unit 4.
In this embodiment, the first, second, and third roll sheets 101,
102, and 103 (FIG. 2) are positioned in the sheet widthwise
direction by the respective corresponding sleeves 113 (FIG. 4).
Therefore, the positions of the side portions and the width of each
roll sheet correspond to the positions of the scale values of the
linear scale 405. A memory (ROM) 409 connected to the control
circuit 406 prestores the positions of the side portions and the
width of each roll sheet on the basis of the counter value of the
encoder pulse counter 407. Although the dimensions of the sheets
101, 102, and 103 change with changes in the environmental
temperature and humidity, the data stored in this memory 409 are
counter values based on the nominal dimensions.
A method of measuring the leading edge position of each sheet by
using the sensor S4 of the carriage unit 4 will be described below
with reference to FIGS. 8 and 9. In FIG. 9, the X axis indicates
the moving direction of the carriage unit 4, and the Y axis
indicates the moving direction of each sheet when the platen roller
501 rotates.
FIG. 9 shows a state in which the sensor S4 moves relative to the
sheet 101, 102, or 103. In the following explanation, a method of
measuring the leading edge position of the sheet 101 will be
described as an example. Note that the same measurement method can
be applied to the sheets 102 and 103 and so a detailed description
thereof will be omitted.
When the platen roller 501 is rotated by the motor 117, an encoder
117a outputs pulses synchronized with the rotation of the motor
117. The pulse outputs from the encoder 117a are applied to a motor
pulse counter 410 via the control circuit 406. The motor pulse
counter 410 counts the pulse outputs and detects the leading edge
of the sheet 101.
Note that FIG. 9 illustrates the method of detecting the leading
edge of the sheet on the downstream side of the platen roller 501.
However, the leading edge of the sheet can be roughly detected by
sensors S1, S2, and S3 provided in a one-to-one correspondence with
the sheets 101, 102, and 103 on the upstream side of the platen
roller 501. Note also that the control circuit (CPU) 406, the
encoder pulse counter 407, the memory (ROM) 409, and the motor
pulse counter 410 are incorporated into a controller 7 arranged
behind the platen unit 5 in the recording station 2 (FIG. 13). When
in operation, this controller 7 is always cooled by the air drawn
by suction by the suction chamber described previously.
A method of measuring the posture of any of the sheets 101, 102,
and 103 by detecting the positions of the side edges and the
leading edge of the sheet by using the sensor S4 of the carriage
unit 4 will be described below with reference to FIG. 9.
First, the leading edge of the sheet is detected by the
corresponding one of the sensors S1, S2, and S3. On the basis of
the detected data, the rotation of the platen roller 501 is
controlled and the leading edge of the sheet is positioned
downstream of the sensor S4 and upstream of the image recording
unit 401.
The carriage unit 4 is then moved in the X-axis direction from the
home position. When the sensor S4 detects a position A of one side
edge of the sheet, the scale value of the linear scale 405 (FIG. 8)
is read by the linear sensor 404 (FIG. 8), thereby measuring the
distance from the home position to the side-edge position A. The
measured value from the linear sensor 404 is compared with the
stored value in the memory 409 (FIG. 8). If the difference is
within a previously stored allowable range, the measurement is
continued. If the difference exceeds the allowable range, it is
determined that the sheet is skewed, and sheet position error
processing is executed.
To continue the measurement, while the sheet is conveyed backward,
i.e., upstream, a leading-edge position B close to one side edge of
the sheet is detected by the sensor S4. Thereafter, on the basis of
the pulse count from the motor pulse counter 410 (FIG. 8), a
distance BC from a position C at which the sheet is stopped to the
leading-edge position B is measured.
The carriage unit 4 is then moved to a position D close to the
other side edge of the sheet while the scale values of the linear
scale 405 (FIG. 8) are read by the linear sensor 404. Subsequently,
while the sheet is conveyed downstream a leading-edge position E
close to the other side edge is detected by the sensor S4.
Thereafter, on the basis of the pulse count from the motor pulse
counter 410, a distance DE from the position D to the leading-edge
position E is measured.
By calculating the difference between the measured distances DE and
BC, the inclination or posture of the leading edge of the sheet is
measured. If this inclination (the difference between the distances
DE and BC) is larger than a previously stored allowable range, it
is determined that the sheet is skewed, and the sheet position
error processing is executed. If the inclination is within the
allowable range, the measurement is continued.
To further continue the measurement, the carriage unit 4 is further
moved to the other side edge of the sheet while the scale values of
the linear scale 405 (FIG. 8) are read by the linear sensor 404.
When the sensor S4 detects a position F of the other side edge of
the sheet, the scale value of the linear scale 405 is read by the
linear sensor 404, thereby measuring a distance AF from the
side-edge position A to the side-edge position F of the sheet.
The pulse count of the movement of the carriage unit 4 over the
distance AF is compared with the pulse count corresponding to the
previously stored width of the sheet. If the difference falls
inside an allowable range, the measurement is completed. If the
difference falls outside the allowable range, sheet size failure
processing is executed.
During the sheet posture measurement as described above, the moving
range of the image recording unit 401 is restricted in the hatched
area in FIG. 9, and so the sheet and the image recording unit 401
do not overlap each other. Therefore, even if the sheet is skewed
to wrinkle, each recording head provided in the image recording
unit 401 is not damaged. Also, even a skew of a wide sheet being
conveyed can be accurately detected within short time periods by
slightly moving the sheet. In addition, the sheet is slightly moved
back and forth immediately downstream of the platen roller 501.
Accordingly, even if the sheet is skewed because it does not
smoothly enter the platen roller 501, no damage is given to the
sheet.
Note that the above sheet posture measurement is performed at any
of the points when automatic conveyance is performed immediately
after each roll sheet is set in the apparatus, before an image
recording operation, and after the image recording operation.
An operation of setting the first, second, and third roll sheets
101, 102, and 103 used in this embodiment in the image forming
apparatus will be described below.
In the image forming apparatus of this embodiment, as illustrated
in FIGS. 1 and 2, the first roll sheet 101 which is widest and
heaviest can be set on the operation side Z (closest to an
operator), and the second and third rolls sheets 102 and 103 which
are comparatively light in weight can be set parallel to each other
at the back of the first roll sheet 101. With this arrangement, the
heaviest first roll sheet 101 can be set closest to the operation
side Z, and this results in the advantage that the operator can
easily set each roll sheet.
As shown in FIG. 15, to set the first, second, and third roll
sheets 101, 102, and 103, a top cover 801 which covers the paper
feed station 1 is opened, and the flanges 101a and 101b attached to
the two end portions of the first roll 101 are placed on the
sleeves 113 and 114 of the paper feed roller 104 (FIG. 4).
Analogously, the flanges of the second and third roll sheets 102
and 103 are placed on the sleeves of the second and third paper
feed rollers 105 and 106, respectively (FIG. 2). Consequently, the
first roll sheet 101 is rotatably supported on the first paper feed
roller 104 and the first support roller 110, and the second and
third roll sheets 102 and 103 are also rotatably supported on the
second and third paper feed rollers 105 and 106 and the second and
third support rollers 112 and 111, respectively (FIGS. 1 and
2).
After the leading edge of the first roll sheet 101 is pulled out,
the first movable guide 118 is once pushed down against the biasing
force of the biasing spring 118b, and the leading edge of the sheet
101 pulled out from the first roll sheet 101 is inserted and nipped
between the first paper feed roller 104 and the pinch roller 107.
Likewise, as illustrated in FIGS. 13 and 14, the leading edges of
the second and third roll sheets 102 and 103 are pulled out, the
second and third movable guides 119 and 120 are once pushed down
against the biasing forces of the biasing springs 119b and 120b,
and the leading edges of the sheets 102 and 103 pulled out from the
second and third roll sheets 102 and 103 are inserted and nipped
between the respective corresponding pairs of the second and third
paper feed rollers 105 and 106 and the pinch rollers 108 and
109.
When the top cover 801 is closed after the first, second, and third
roll sheets 101, 102, and 103 are thus set, a sensor (not shown)
detects the motions of the first, second, and third movable guides
118, 119, and 120, and it is determined that the first, second, and
third roll sheets 101, 102, and 103 are set.
The operations done by the operator are up to closing the top cover
801, and after that the closure of the top cover 801 is detected
and the sensors S1, S2, and S3 check the sheets.
If the leading edge of any of the sheets 101, 102, and 103 is not
detected by the corresponding one of the sensors S1, S2, and S3,
the motor 117 and the clutch 115 (FIG. 4) are selectively driven to
rotate the corresponding one of the first, second, and third paper
feed rollers 104, 105, and 106 in the forward direction, thereby
conveying the sheet until the leading edge of the sheet is detected
by the corresponding one of the sensors S1, S2, and S3. If the
leading edge of the sheet is not detected by the sensor S1, S2, or
S3 after the sheet is conveyed a predetermined amount while the
number of pulses is counted by the motor pulse counter 410 (FIG.
8), a sheet set error is determined. If the leading edge of any of
these roll sheets is already detected by the corresponding one of
the sensors S1, S2, and S3 when the roll sheet is set, the
corresponding one of the first, second, and third paper feed
rollers 104, 105, and 106 is rotated in the reverse direction and
the leading edge of the sheet is again detected.
When the leading edge of each of the sheets 101, 102, and 103 is
detected by the corresponding one of the sensors S1, S2, and S3,
the conveyance of the sheet is stopped. As a consequence, the sheet
is placed in a standby position.
Thereafter, these sheets are selectively fed and image formation
processing is performed for a sheet of a desired size. In the
following explanation, only the processing for the sheet 101 will
be described as an example. Note that the same processing can be
applied to the sheets 102 and 103 and so a detailed description
thereof will be omitted.
When the sensor S1 detects the leading edge of the sheet 101, the
first paper feed roller 104 is driven. The leading edge of the
sheet 101 is guided from the sensor S1 to the guide bar 208, and
the moving direction of the sheet is changed by the thin plate
member 207 sitting by its own weight on the sleeves 210 rotatably
fitted on the guide bar 208. Thereafter, the sheet 101 guided by
the pinch holders 209 and the platen boards 502 is pinched between
the platen roller 501 and the driving pinch rollers 507 and
conveyed to the suction chamber. Since the suction chamber is
evacuated by the suction means 504, the sheet 101 slides in the
sheet conveyance direction T as it is kept in tight contact with
the platen boards 502.
When the leading edge of the sheet 101 passes by the cutter 205,
this leading edge is detected by the sensors S5 and S6 arranged at
almost the same positions as the paper delivery rollers 206
downstream of the cutter 205.
Since the distances from the sensor S1 to the sensors S5 and S6 are
previously set, a sheet conveyance error can be detected by
counting the number of output pulses from the encoder 117a (FIG. 8)
of the motor 117 by using the encoder pulse counter 407 (FIG. 8).
More specifically, the number of output pulses from the encoder
117a is already stored in the memory (ROM) 409 of the controller 7
(FIG. 8). Therefore, the number of pulses output from the encoder
117a while the sheet 101 is actually conveyed is counted by the
encoder pulse counter 407, and the count is compared with the
prestored number of pulses. Consequently, whether the sheet 101 is
conveyed a predetermined amount can be checked.
After the leading edge of the sheet 101 passes by the sensors S5
and S6 and is conveyed a predetermined amount, the conveyance of
the sheet 101 is stopped. The cutter 205 is operated to cut the end
portion of the sheet, and the cut sheet is delivered by the paper
delivery rollers 206. As a consequence, the leading edge of the
sheet can have a clear cut surface with no scratches. The sheet 101
from which the end portion is cut is returned to the standby
position described above by reversely rotating the platen roller
501. Note that even during this return the leading edge of the
sheet is drawn to the platen boards 502 by suction by the suction
means 504.
In this construction, since the cutter 205 is arranged downstream
of the platen boards 502, dust particles of a sheet produced when
the sheet is cut freely fall and do not scatter onto the image
recording unit 401 (FIG. 9). Also, dust particles attached to the
leading edge of a sheet to be returned are drawn by suction by the
suction means 504 (FIG. 5) when the sheet passes through the
suction chamber. This prevents dust particles produced when the
sheet 101 is cut from adhering to the sheet 101.
The peripheral velocity of each of the paper feed rollers 104, 105,
and 106 is set to be higher by about 1% than that of the platen
roller 501, and the peripheral velocity of the paper delivery
rollers 206 is set to be higher by 5% than that of the platen
roller 501. Accordingly, after the leading edge of a sheet is
nipped between the platen roller 501 and the driving pinch roller
507 when the sheet is conveyed in the sheet conveyance direction T,
the conveying operation by the corresponding paper feed roller is
released by the clutch 115 (FIG. 4), and the sheet is conveyed only
by the rotation of the platen roller 501. When the sheet is
conveyed in the reverse direction, the corresponding paper feed
roller is driven by the clutch and the sheet is conveyed by both
the platen roller 501 and the paper feed roller.
An operation of forming an image on the widest first roll sheet 101
will be described below.
The sheet 101 in the standby position is fed a predetermined length
by the set operation described above. The leading edge of the sheet
101 is positioned downstream of the sensor S4 in the carriage unit
4 and upstream of the image recording unit 401 by the platen roller
501 and the driving pinch rollers 507. As described earlier, the
sensor S4 checks the width and position of the sheet 101 and the
inclination of the leading edge. This check is done to previously
detect an abnormal state such as a shrinkage of the sheet 101
occurring due to an environmental change while the sheet is
standing by or a skew of the sheet 101 occurring while the sheet is
conveyed from the standby position to the image recording unit 401.
If such an abnormal state is detected by this check, a sheet set
error is output and the sheet 101 is conveyed in the reverse
direction until the leading edge comes out from the first paper
feed roller 104. If there is no such problem, on the other hand, an
image recording operation to be described below is started.
Image recording performed in the order of black (K), cyan (C),
magenta (M), and yellow (Y) will be described below.
After the sensor S4 detects the leading edge of the sheet 101, the
sheet 101 is conveyed to a position at which the leading edge of
the sheet opposes the recording head K for ejecting black ink. Only
black ink is then recorded on the sheet 101 by scanning the
carriage unit 4 forward and backward.
In this reciprocating recording mode, when the forward motion of
the carriage unit 4 is completed, the platen roller 501 is
intermittently driven to convey the sheet 101 to a position at
which the leading edge of the sheet 101 opposes the recording head
C for ejecting cyan ink. When the backward motion is started, ink
components of two colors, black and cyan, are recorded on the sheet
101.
Before the forward motion is again started, the sheet 101 is
conveyed to a position where the leading edge of the sheet 101
opposes the recording head M for ejecting magenta ink. When the
forward motion is started, ink components of three inks, black,
cyan, and magenta, are recorded on the sheet 101.
Before the subsequent backward motion is started, the sheet 101 is
conveyed to a position where the leading edge of the sheet 101
opposes the recording head Y for ejecting yellow ink. When the
backward motion is started, ink components of all of the four
colors are recorded on the sheet 101.
During this image recording operation, the sheet 101 is
intermittently conveyed in synchronism with the motion of the
carriage unit 4 while being in tight contact with the platen boards
502. The sheet 101 is then nipped between the paper delivery
rollers 206.
As described above, the image recording can be started before the
leading edge of the sheet 101 is nipped between the paper delivery
rollers 206. Consequently, it is possible to minimize a
non-recorded portion formed in the end portion of the sheet 101.
Note that the image recording is completed in the reverse order by
first completing printing of black and finally completing printing
of yellow.
After the image recording is completed, the sheet 101 is conveyed
until a cut boundary portion comes to the position of the cutter
205. The carriage unit 4 is moved to the home position, and the
surface of each recording head is covered with a protection cap.
Thereafter, the cut boundary portion is cut by the cutter 205.
As described above, the cut processing is performed after the
surface of each recording head is covered with the protection cap.
Consequently, it is possible to prevent paper dust produced by the
cut from attaching to the surfaces of the recording heads.
An operation of continuously recording different images on the same
sheet 101 will be described below.
Assume that when image recording is started immediately after the
preceding image recording is completed, the sheet 101 is
intermittently conveyed a feed length L.
If a cut boundary portion in an already recorded image region of
the sheet 101 passes by the cut position of the cutter 205 while
the sheet 101 is conveyed the feed length L, the sheet 101 is not
conveyed the feed length L. That is, the sheet 101 is conveyed a
length a (a<L) by which the cut boundary portion in the recorded
image region is placed in the cut position of the cutter 205.
When the sheet 101 is conveyed the length a (a<L), the carriage
unit 4 is retracted to the home position before the sheet is cut.
After the recording heads are covered with the protection caps, the
cut boundary portion of the sheet 101 is cut.
After the sheet is cut, the operation of the apparatus is paused
until dust particles of paper freely fall and are removed by being
drawn to the suction means 504 by suction. Thereafter, the sheet
101 is conveyed a length b (b=L-a). The result is that the sheet
101 is conveyed the feed length L.
The protection caps are then detached from the recording heads, and
the subsequent image recording is started.
With this control different images can be continuously recorded on
the same sheet 101, and consequently the image recording time can
be shortened. Also, since each recording head is covered with the
protection cap when the sheet is cut, paper dust adversely
affecting the image recording does not adhere to the recording
heads.
An image recording operation in a leading-and-trailing-edge no
margin mode will be described below. To perform this operation, the
no margin mode is chosen from the operation panel (not shown) of
the image forming apparatus.
In the no margin mode, image recording is started after a margin
with a predetermined length is assured in the leading edge of the
sheet 101. The length of this margin is a minimum length with which
the sheet 101 can be delivered by the paper delivery rollers
206.
In this no margin mode, the leading-edge margin is cut by the
cutter 205 at the image recording start position. As in the case of
the conventional sheet trailing edge cut sequence, the sheet is
first conveyed only the length a (a<L) with respect to the feed
length L, and the image leading edge position is cut. The sheet is
then conveyed the remaining length b (b=L-a). While the sheet is
cut, the carriage unit 4 is kept retracted to the home position,
and the trailing-edge margin of the sheet 101 also is cut at the
end position of the image recorded area. However, in some instances
the preceding image somewhat extends to the leading edge of the
following sheet 101 for the subsequent image recording due to an
error during the sheet conveyance. If this occurs, a margin is
formed in the leading edge of the sheet 101 for the subsequent
image recording, and this margin is cut. As a result, the extended
recorded image is removed together with the margin. In this case,
however, the leading and trailing edges of the sheet 101 in the
recorded image region are wasted in removing the extended recorded
image.
An operation of simultaneously recording images on the second and
third roll sheets 102 and 103 will be described below with
reference to FIG. 6.
In plotters or the like apparatuses, a general approach is to
rearrange input images in accordance with the sizes of the images
by using a function called an auto-layout function, thereby
printing the images with a high efficiency.
In this embodiment, A2- and A1-size images are recorded on the
594-mm wide second roll sheet 102 and at the same time A4- and
A3-size images are recorded on the 297-mm wide third roll sheet
103.
As shown in FIG. 6, images of different sizes indicated by
reference symbols A to F are recorded on the sheets 102 and 103
conveyed from the second and third roll sheets. Note that the
broken lines in FIG. 6 represent the cut boundaries to be cut by
the cutter 205.
Prior to performing image recording, the inclinations of the
leading edges and the like conditions of the sheets 102 and 103 are
independently checked (skew check) by the method described earlier.
Image recording data is corrected so that the relationships between
the leading edges of the sheets 102 and 103 and the image recording
are held constant for the sheets 102 and 103.
When a plurality of images are simultaneously recorded on the
sheets 102 and 103 in this way, the pause time of the carriage unit
4 in the end portion of the movement is relatively saved. This
achieves a reduction of the recording time.
If the cut boundary of the image thus recorded passes by the cut
position of the cutter 205, the sheet is not conveyed a
predetermined feed amount at once. That is, as in the operation
described previously, the sheet 102 or 103 is first conveyed until
the cut boundary is placed in the cut position of the cutter
205.
When the cut boundary of the sheet 102 or 103 is placed in the cut
position of the cutter 205, the movable blade 205b arranged in a
gap L is moved to cut the cut boundary of the sheet to be cut.
Thereafter, the sheet 102 or 103 is conveyed the remaining amount.
As a consequence, the sheet 102 or 103 is conveyed a predetermined
feed amount. The predetermined amount is a feed amount when the
sheet is not to be cut.
Note that the movable blade 205b (FIG. 13) of the cutter 205 is
arranged in the gap L between the two sheets 102 and 103 so that
the cutter 205 acts only on one of the simultaneously conveyed
sheets 102 and 103 to be cut. The movable blade 205b is moved in
one direction from this gap L to cut the sheet 102 and moved in the
other direction to cut the sheet 103.
If the cutter 205 is of a type which reciprocates in the sheet
widthwise direction, the movable blade 205b of the cutter 205 is
once stopped in the gap L by detecting the position of the blade
205b. To cut the widest sheet 101, it is only necessary to stop the
blade outside the sheet width.
If the cutter 205 is mounted on the carriage unit 4 and its blade
cuts the sheet by selectively entering and leaving the sheet
conveyance path, it is only necessary to make the blade selectively
act on the sheet 102 or 103 to be cut.
To simultaneously record images on the sheets 102 and 103 by using
the auto-layout function as described above, a feed length to each
subsequent cut boundary is calculated for each sheet before image
recording is performed. If the difference between the calculated
feed lengths is a predetermined value or smaller, simultaneous
image formation is performed. If the difference exceeds the
predetermined value, simultaneous recording is not performed. With
this control it is possible to prevent the two sheets from being
conveyed a long length while images are recorded only on one
sheet.
The processing station 3 which processes the sheet on which an
image of a predetermined size is recorded and which is cut by the
cutter 205 as described above will be described below.
As shown in FIG. 1, the processing station 3 is arranged below the
paper delivery rollers 206 and includes a table 301 on which the
sheets 101, 102, and 103 can be placed. This table 301 is arranged
with its one end portion on the operation side Z elevated so that
an acute angle is formed with respect to the sheet conveyance
direction T (a conveyance guide 303 to be described below).
The processing station 3 also includes the conveyance guide 303, a
plurality of fans 304, and nip rollers 302. The conveyance guide
303 guides the sheets 101, 102, and 103, delivered from the paper
delivery rollers 206, nearly directly below. The fans 304 are
arranged throughout the width of the sheet on the side away from
the sheet conveyance side of the conveyance guide 303. The nip
rollers 302 are pivotally arranged on the lower end portion of the
conveyance guide 303.
One end portion of the table 301 on the operation side Z is
pivotally supported. The other end portion of the table 301
extending toward the nip rollers 302 is biased in the direction of
the nip rollers 302 by a biasing spring 306 arranged below this end
portion. Consequently, the upper surface of this end portion of the
table 301 is always pressed against the nip rollers 302.
As illustrated particularly in FIG. 19, an arcuated stopper 305 is
arranged near this end portion of the table 301 in a direction
perpendicular to the tangent passing the point of contact at which
the table 301 is pressed against the nip rollers 302.
As shown in FIG. 10A, the sheet 101, 102, or 103 on which an image
is recorded is delivered by the paper delivery rollers 206 and
conveyed down as its non-recorded surface is guided by the
conveyance guide 303. Note that since the sheet is a roll sheet,
the leading edge of the sheet is slightly curled toward the
conveyance guide 303.
As illustrated in FIG. 10B, the leading edge of the sheet comes out
from the conveyance guide 303 and, partly because of its curl,
comes in contact with the contact portions between the table 301
and the nip rollers 302. When the leading edge of the sheet
contacts well, the nip rollers 302 are slightly rotated by a
driving motor (not shown). The amount of rotation need only be an
amount with which the leading edge of the sheet is nipped between
the nip rollers 302 and the table 301 and abuts against the stopper
305.
After the leading edge of the sheet abuts against the stopper 305
to stop, the sheet and the nip rollers 302 slip relative to each
other. The friction coefficient of the nip rollers 302 is set to be
slightly larger than the friction coefficient of the sheet. This
prevents the sheet from being buckled.
Even after the leading edge of the sheet abuts against the stopper
305, the trailing edge of the sheet is kept recorded and conveyed.
When a predetermined amount of recording is completed, therefore,
the central portion of the sheet separates from the conveyance
guide 303 and forms a loop.
As shown in FIG. 10C, the fans 304 provided in the conveyance guide
303 are driven from the timing at which the leading edge of the
sheet is nipped by the nip rollers 302 to the timing at which the
trailing edge of the sheet is cut by the cutter 205, separated from
the paper delivery rollers 206, and stacked. The trailing edge of
the sheet is pushed toward one end of the table 301 by this wind
pressure.
As shown in FIG. 10D, the trailing edge of particularly a long
sheet hangs down from the table 301, and the leading edge of the
sheet is nipped and held by the nip rollers 302.
As illustrated in FIG. 10E, by repeating the above operation sheets
whose leading edges are nipped by the nip rollers 302 are
sequentially stacked on the table 301.
The table 301 is pushed down in accordance with the thickness of
the stacked sheets. The biasing spring 306 has a biasing force
capable of resisting the weight corresponding to the thickness of
the sheets stacked on the table 301 and holding the sheets so that
the hanging trailing edges of the sheets do not fall.
The table 301 used in this embodiment is cut in at least the
boundary between the sheets 102 and 103, and these cut tables 301
are independently biased. Accordingly, even when the roll sheet 103
is used often and only a small amount of the roll sheet 102 is
used, the top surfaces of these sheets stacked on the tables 301
are nearly even with each other. Therefore, even if a wide sheet
such as the roll sheet 101 is to be subsequently stacked on the
stacked sheets 102 and 103, the sheet 101 is stably stacked with no
trouble because the top surfaces of the sheets 102 and 103 are
almost flush with each other. The table 301 also has the advantage
that sheets having different lengths can be sequentially stacked.
Furthermore, the trailing edge of each sheet is pushed away from
the sheet stacking position by the wind pressure of the fans 304.
Therefore, the trailing edge of each sheet does not block the
leading edge of the next sheet to be stacked.
The processing station 3 according to a modification of this
embodiment will be described below with reference to FIGS. 11 and
12.
As shown in FIG. 11, the processing station 3 of this modification
includes a plurality of paper delivery trays arranged below the
paper delivery rollers 206 to receive recorded sheets in accordance
with the sheet sizes. These paper delivery trays can be
horizontally moved back and forth with respect to the operation
side Z (in directions indicated by the arrows in FIG. 11).
Each paper delivery tray is inclined a predetermined angle and has
a sheet inlet in one end portion opposing the paper delivery
rollers 206 and a sheet outlet in the other end.
As illustrated in FIG. 12, when A4- and A3-size recorded sheets are
cut from the 297-mm wide roll sheet 103, a paper delivery tray 601
arranged on the operation side Z receives the A4-size sheets, and a
paper delivery tray 602 arranged at the back of the paper delivery
tray 601 when viewed from the operation side Z receives the A3-size
sheets. A2-size sheets cut from the 594-mm wide roll sheet 102 are
received by a paper delivery tray 603 juxtaposed to the paper
delivery tray 602 in the sheet widthwise direction. When A1- and
A0-size sheets are cut from the 841-mm wide sheet 101, these A1-
and A0-size sheets are received by a paper delivery tray 604
arranged at the back of the juxtaposed paper delivery trays 602 and
603.
Accordingly, the processing station 3 is moved a predetermined
amount in a predetermined direction in accordance with the size of
a sheet to be delivered so that a paper delivery tray of a desired
size is positioned below the paper delivery rollers 206.
The paper delivery tray 604 for receiving A1- and A0-size sheets
has a depth designed to meet the A1 size. To receive an A0-size
sheet, therefore, when the leading edge of the sheet reaches the
bottom of the paper delivery tray 604 the processing station 3 is
moved toward the operation side Z in synchronism with the paper
delivery operation, so that the trailing edge of the sheet hangs
down from the sheet inlet of the paper delivery tray 604. As a
result, A0-size sheets are received as they are nearly folded in
two. Accordingly, to protect sheets from damages, an arcuated
portion 604b is formed at the sheet inlet of the paper delivery
tray 604. Note that sheet push members 605 are arranged at the
sheet outlet of each paper delivery tray.
The paper delivery trays are so arranged that the size of a sheet
capable of being received increases from the front side to the rear
side when viewed from the operation side Z. Therefore, all sheet
outlets formed in the lower ends of these paper delivery trays are
exposed to the operation side Z. This allows an operator to pick up
sheets of a desired size without moving the processing station 3
even while sheets are being received. Also, since the paper
delivery trays are arranged in the sheet widthwise direction in
accordance with the arrangement of the first, second, and third
roll sheets 101, 102, and 103 set in the apparatus, the depth of
the processing station 3 can be decreased. Consequently, the
processing station 3 need only be moved a little and hence does not
move to protrude from the apparatus. Accordingly, the movement does
not interfere with, e.g., walking in front of the apparatus.
An operation of releasing a paper jam will be described below.
As illustrated in FIG. 15, the first, second, and third roll sheets
101, 102, and 103 are arranged in the paper feed station 1 of the
image forming apparatus of this embodiment and all these roll
sheets are accommodated in the top cover 801.
One end portion of the top cover 801 at the back of the apparatus
when viewed from the operation side Z is pivotally supported, and
the other end portion of the top cover 801 at the front of the
apparatus can be opened. In the recording station 2, a front cover
802 capable of being opened about its lower portion is arranged on
the operation side Z opposing the platen boards 502.
Inside the top cover 801, as shown in FIG. 16, the lever 212
extends on the side of the roll sheets 101, 102, and 103 via the
link mechanism 211 arranged outside the first frame 201. This lever
212 is connected to the guide bar 208 via the link mechanism 211.
Therefore, by operating the lever 212 after the top cover 801 is
opened, the driving pinch rollers 507 can be separated from the
platen roller 501 (FIG. 17). As a result, the upstream ends of the
sheets are nipped between the paper feed rollers 104, 105, and 106
and the pinch rollers 107, 108, and 109, respectively, and their
downstream ends are nipped by the paper delivery rollers 206.
The nipping force of the paper delivery rollers 206 is extremely
small compared to the conveying forces of other rollers (not
shown). Accordingly, the leading edge of a jammed sheet can be
easily returned to the sheet roll by manually rotating the
corresponding paper feed roller in the reverse direction.
It is also possible to release the nipping forces acting on the
sheets by the paper feed rollers and the pinch rollers by pushing
down the first, second, and third movable guides 118, 119, and 120
against the biasing forces of the biasing springs 118b, 119b, and
120b, respectively (FIGS. 13 and 14). The result is that the
leading edge of a jammed sheet can be easily returned to the sheet
roll.
The first conveyance path (FIG. 13) formed by the first movable
guide 118 and the first fixed guide 122 can be directly seen from
an operation side Z" (FIG. 15) by opening the top cover 801. Also,
the second conveyance path (FIG. 13) formed by the second movable
guide 119 and the second fixed guide 121 and the third conveyance
path (FIG. 14) formed by the third movable guide 120 and the second
fixed guide 121 can be directly seen from the above, L (FIG. 15),
of the apparatus by opening the top cover 801.
Accordingly, even if a paper jam as described above occurs, the
operator can easily and reliably remove the jammed sheet by
visually checking the jammed position.
When a paper jam occurs, the carriage unit 4 in the recording
station 2 is so controlled as to retract to the home position
arranged outside the first frame 201. Therefore, by opening the
front cover 802 (FIG. 15) the operator can remove the jammed sheet
while directly seeing the portion near the platen boards 502 from
the operation side Z.
In the processing station 3 (FIG. 15) used in this embodiment, no
apparatus constituent members are arranged on a lower operation
side Z' downstream of the paper delivery rollers 206 and opposing
the conveyance guide 303. This allows the operator to readily
perform the paper jam processing from the lower operation side
Z'.
On the other hand, the processing station 3 (FIGS. 11 and 12)
according to the modification of this embodiment is so controlled
that, when a paper jam takes place, the overall processing station
3 retracts to the back side of the apparatus beyond a normal moving
distance. If this is the case, the paper delivery tray 601 arranged
closest to the operation side is retracted to behind the paper
delivery rollers 206. Consequently, the operator can readily
perform the paper jam processing on the downstream side of the
paper delivery rollers 206. Furthermore, even if a paper jam occurs
in any of the paper delivery trays, the whole processing station 3
can be pulled out beyond a normal moving range toward the operation
side by inputting a command from the operation panel (not shown).
Accordingly, the operator can easily remove the jammed sheet from
the paper delivery tray while directly seeing the inlet of the
paper delivery tray.
An image forming apparatus according to the second embodiment of
the present invention will be described below. The image forming
apparatus of this embodiment is so designed as to be able to record
a desired image on a sheet of a predetermined size. It is possible
to use, e.g., recording paper, a sheet of paper, a plastic film, or
cloth as the sheet.
In the following explanation, an image forming apparatus using a
sheet of paper as an image recording sheet will be described as an
example.
As shown in FIGS. 21 and 22, the image forming apparatus of this
embodiment includes a paper feed station 1, a recording station 2,
and a processing station (not shown). The paper feed station 1 can
accommodate a plurality of roll sheets each formed by winding a
sheet of a predetermined size into a roll. The recording station 2
records a desired image on a sheet fed from the paper feed station
1. The processing station delivers the sheet on which the image is
recorded by the recording station 2.
In this embodiment, it is assumed that a roll sheet formed by
winding a 841-mm wide sheet 101 into a roll is an L-size roll sheet
101, a roll sheet formed by winding a 594-mm wide sheet 102 into a
roll is an M-size roll sheet 102, a roll sheet formed by winding a
297-mm wide sheet 103 into a roll is an S-size roll sheet 103, and
a roll sheet formed by winding a 914-mm wide sheet 100 into a roll
is an LL-size roll sheet 100 (FIGS. 28A to 28C).
As shown in FIG. 20, a front paper feed roller 902, a front support
roller mechanism 904, and a front support roller 906 are arranged
in the paper feed station 1 so that the LL-size roll sheet 100 or
the L-size roll sheet 101 can be set on the front side when viewed
from an operation side Z.
The front paper feed roller 902 is rotatably supported by bearings
(not shown) between first and second frames 201 and 202. A driving
force transmitted from a motor 117 (FIGS. 4 and 22) to a driving
belt 116 (FIG. 4) via a worm mechanism is transmitted to the paper
feed roller 902 via a clutch 115 (FIG. 4). The paper feed roller
902 is so designed that the friction coefficient on the outer
circumferential surface in a central portion is higher than that in
the other portion.
The front support roller mechanism 904 is rotatably supported
parallel to the front paper feed roller 902 by the first frame 201
via a bearing (not shown).
The front support roller 906 is rotatably supported coaxially with
the support roller mechanism 904 and parallel to the paper feed
roller 902 by the second frame 202 via a bearing (not shown).
Also, rear paper feed rollers, rear support roller mechanisms, and
rear support rollers are arranged in the paper feed station 1 in
order that the LL-size roll sheet 100, the L-size roll sheet 101,
the M-size roll sheet 102, and the S-size roller sheet 103 can be
selectively set on the rear side when viewed from the operation
side Z. A driving force transmitted from a motor (not shown) to a
driving belt (not shown) via a worm mechanism is transmitted to the
rear paper feed rollers via a clutch (not shown). Each of these
rear paper feed rollers is so designed that the friction
coefficient on the outer circumferential surface in a central
portion is higher than that in the other portion.
On the rear side of the paper feed station 1, first and second
center frames 908 and 910 are arranged to be equally spaced between
the first and second frames 201 and 202. These center frames 908
and 910 partition the rear side of the paper feed station 1 into
three areas A, B, and C.
In the area A, a rear paper feed roller 912 is rotatably supported
between the first frame 201 and the first center frame 908 by
bearings (not shown). A rear support roller mechanism 914 is
rotatably supported parallel to the rear paper feed roller 912 by
the first frame 201 via a bearing (not shown). A rear support
roller 916 is rotatably supported coaxially with the support roller
mechanism 914 and parallel to the paper feed roller 912 by the
first center frame 908 via a bearing (not shown).
In the area B, a rear paper feed roller 918 is rotatably supported
between the first and second center frames 908 and 910 by bearings
(not shown). A rear support roller mechanism 920 is rotatably
supported parallel to the rear paper feed roller 918 by the first
center frame 908 via a bearing (not shown). A rear support roller
922 is rotatably supported coaxially with the support roller
mechanism 920 and parallel to the paper feed roller 918 by the
second center frame 910 via a bearing (not shown).
In the area C, a rear paper feed roller 924 is rotatably supported
between the second frame 202 and the second center frame 910 by
bearings (not shown). A rear support roller mechanism 926 is
rotatably supported parallel to the rear paper feed roller 924 by
the second center frame 910 via a bearing (not shown). A rear
support roller 928 is rotatably supported coaxially with the
support roller mechanism 926 and parallel to the paper feed roller
924 by the second frame 202 via a bearing (not shown).
The three rear paper feed rollers 912, 918, and 924 arranged in the
areas A, B, and C are positioned coaxially with each other and
parallel to the front paper feed roller 902.
Sleeves 902a, 912a, 918a, and 924a are formed in end portions on
one side of the front and rear paper feed rollers 902, 912, 918,
and 924, and step portions 902b, 912b, 918b, and 924b are formed in
end portions on the other side of these rollers 902, 912, 918, and
924. A step portion 924c on which a flange 101a (FIGS. 21 and 28A)
of the L-size roll sheet 101 can fit is also formed in a position
shifted from the center to the other end of the rear paper feed
roller 924 arranged in the area C.
The first and second center frames 908 and 910 are provided with
coupling mechanisms (FIGS. 23A and 23B) which can rotate the rear
paper feed rollers 912, 918, and 924 independently of each
other.
These coupling mechanisms will be described below with reference to
FIGS. 23A and 23B. Note that since these coupling mechanisms have
the same construction, only the coupling mechanism of the first
center frame 908 will be described and a description of the
coupling mechanism of the second center frame 910 will be
omitted.
As shown in FIGS. 23A and 23B, the first center frame 908 rotatably
supports one end of the rear paper feed roller 912 via a bearing
930 and also rotatably supports one end of the rear paper feed
roller 918 via a bearing 932.
A gear 934 having a smaller diameter than the diameter of the paper
feed roller 912 is arranged between the step portion 912b of the
paper feed roller 912 and the bearing 930. A conduction gear 936
meshes with the gear 934.
The conduction gear 936 is fitted on one end of a gear shaft 938
which is rotatably supported by the first center frame 908. A slide
gear 942 is fitted on the other end of the gear shaft 938 and is
always biased toward the conduction gear 936 by a biasing spring
940. This slide gear 942 is slidable along the gear shaft 938 and
unable to rotate.
A small-diameter shaft 944 is formed in one end portion of the
paper feed roller 918 to extend from the sleeve 918a. A gear 946
capable of meshing with the slide gear 942 is formed in the
extending end portion of the shaft 944. When a roll sheet of a
given size is not set, the gear 946 and the slide gear 942 are kept
meshed by the biasing spring 940.
Assume, for example, that the M-size roll sheet 102 is set across
the areas B and C (FIG. 20) as illustrated in FIGS. 21 and 23B. The
M-size roll sheet 102 is set in the areas B and C as it is
positioned in the axial direction by placing a flange 102a on the
rear support roller mechanism 920, the sleeve 918a of the rear
paper feed roller 918, the step portion 924b of the rear paper feed
roller 924, and the rear support roller 928.
When the M-size roll sheet 102 is set as above, an operation arm
948a of an actuator 948 which is pivotally supported by the first
center frame 908 is urged by the flange 102a. A pressure arm 948b
of the actuator 948 urges the slide gear 942 against the biasing
force of the biasing spring 940. As a result, the slide gear 942
and the gear 946 are released from the meshed state. This allows
the paper feed roller 912 in the area A and the paper feed roller
918 in the area B to rotate independently of each other. Therefore,
when, for example, the S-size roll sheet 103 is set in the area A
(FIG. 20) and the M-size roll sheet 102 is set across the areas B
and C (FIG. 20), as illustrated in FIG. 21, and the image forming
apparatus is driven by an operation panel 952 (FIG. 29) provided on
a top cover 801, it is possible to feed a desired sheet from at
least one of the M-size roll sheet 102 and the S-size roll sheet
103.
When the M-size roll sheet 102 is removed as shown in FIG. 23A, the
urging force of the operation arm 948a of the actuator 948 is
released. Consequently, the slide gear 942 is biased by the biasing
spring 940 and meshed with the gear 946. This allows the paper feed
roller 912 in the area A and the paper feed roller 918 in the area
B to rotate together.
The operation state (FIGS. 23A and 23B) of the actuator 948 is
constantly monitored by a detection circuit 950. On the basis of an
output detection signal from the detection circuit 950 to the
operation panel 952 (FIG. 29), a display unit 952a of the operation
panel 952 displays the set positions and set conditions of the roll
sheets 100, 101, 102, and 103. Consequently, the operator can
recognize the set positions and set conditions of the roll sheets
100, 101, 102, and 103 set in the image forming apparatus without
opening the top cover 801 (FIG. 29).
Assume that as shown in FIG. 21, the S-size roll sheet 103 is set
in the area A (FIG. 20), the M-size roll sheet 102 is set across
the areas B and C (FIG. 20), and the L-size roll sheet 101 is set
in the front.
To rewind the sheets 101, 102, and 103 while image recording is
performed for a given one of the sheets 101, 102, and 103 or after
predetermined image recording is completed, the sheets 101, 102,
and 103 are rewound by driving the support roller mechanisms 904,
914, 920, and 926.
The support roller mechanisms 904, 914, 920, and 926 will be
described below with reference to FIG. 24. Note that since these
support roller mechanisms have the same construction, only the
front support roller mechanism 904 will be described below and
descriptions of the other support roller mechanisms 914, 920, and
926 will be omitted.
As shown in FIG. 24, the support roller mechanism 904 consists of a
support roller 954 and an electromagnetic clutch 956. The support
roller 954 is made from a material (e.g., rubber) having a certain
high friction coefficient and is freely rotatable. The
electromagnetic clutch 956 has a second meshing portion 956a which
can mesh with a first meshing portion 954a of the support roller
954. The electromagnetic clutch 956 is connected to a reduction
gear 960 via a shaft 958, and this reduction gear 960 is connected
to a reverse motor 962. The shaft 958 is fixed to a rotating shaft
(not shown) of the reduction gear 960 by a machine screw 964.
When the L-size roll sheet 101 is set in the front of this
construction, the flange 101a of the L-size roll sheet 101 is
placed on the support roller 954 of the support roller mechanism
904.
To feed the sheet 101 in this state, the support roller 954 is
freely rotated as the flange 101a rotates because the first and
second meshing portions 954a and 956a are released from the meshed
state.
To rewind the sheet 101, the reverse motor 962 and the
electromagnetic clutch 956 are operated by operating an operation
key 952b (FIG. 29) on the operation panel 952. Consequently, the
second meshing portion 956a meshes with the first meshing portion
954a of the support roller 954. At the same time, the rotational
force of the reverse motor 962 is reduced by the reduction gear 960
and transmitted to the electromagnetic clutch 956. As a result, the
support roller 954 is reversely rotated to rewind the sheet 101 to
the L-size roll sheet 101.
During the paper feed operation or the rewind operation as
described above, a given one of the roll sheets 101, 102, and 103
is conveyed along one of conveyance paths (FIG. 26) formed between
movable guides 966 and 968 and fixed guides 122 and 121 having a
desired rigidity.
As shown in FIGS. 21 and 26, the sheets 101, 102, and 103 are
selectively fed from the L-, M-, and S-size roll sheets 101, 102,
and 103 such that the sheet 101 is conveyed along the conveyance
path (FIG. 26) formed between the fixed guide 122 and the movable
guide 966 and the sheets 102 and 103 are conveyed along the
conveyance path (FIG. 26) formed between the fixed guide 121 and
the movable guide 968.
In order to smoothly and stably feed the sheets 101, 102, and 103,
a plurality of rotatable pinch rollers 970 and 972 are arranged on
the movable guides 966 and 968 along a direction perpendicular to a
sheet conveyance direction T (FIGS. 25A and 25B).
As shown in FIGS. 25A, 25B, and 26, the pinch rollers 970 and 972
are rotatably held in brackets 974 and 976 attached to the rocking
distal end portions of the rockingly supported movable guides 966
and 968, respectively. The brackets 974 and 976 are always biased
against their weights toward the paper feed rollers 902, 912, 918,
and 924 by biasing springs 978 and 980, respectively. As a
consequence, the pinch rollers 970 are always evenly and tightly
urged against the outer circumferential surface of the front paper
feed roller 902 (FIG. 25A), and the pinch rollers 972 are always
evenly and tightly urged against the outer circumferential surfaces
of the rear paper feed rollers 912, 918, and 924 (FIG. 25B).
In the above explanation, the L-, M-, and S-size roll sheets 101,
102, and 103 are set as an example. However, the same effect can be
obtained even when the LL-size roll sheet 100 is set as illustrated
in FIG. 28A.
An operation of feeding the sheets 100, 101, 102, and 103 from the
paper feed station 1 to the recording station 2 will be described
below with reference to FIG. 26. In the following explanation, an
operation of feeding the sheets 101, 102, and 103 from the L-, M-,
and S-size roll sheets 101, 102, and 103 set as shown in FIG. 21
will be described as an example.
First, the movable guide 966 is pushed down against the biasing
force of the biasing spring 978, and the leading edge of the sheet
101 of the L-size roll sheet 101 is inserted and nipped between the
front paper feed roller 902 and the pinch rollers 970. Also, the
movable guide 968 is pushed down against the biasing force of the
biasing spring 980, and the leading edges of the sheets 102 and 103
of the M- and S-size roll sheets 102 and 103 are inserted and
nipped between the rear paper feed rollers 912, 918, and 924 and
the pinch rollers 972.
When the image forming apparatus is driven by operating the
operation panel 952 (FIG. 29) in this state, the rotational driving
force of a platen roller 501 which is rotated by the motor 117
(FIG. 22) is transmitted to a desired one of the paper feed rollers
902, 912, 918, and 924. Consequently, the desired one of the paper
feed rollers 902, 912, 918, and 924 is rotated to feed one of the
sheets 101, 102, and 103 from the L-, M-, and S-size roll sheets
101, 102, and 103.
For example, the sheet 101 fed from the L-size roll sheet 101 is
conveyed along the conveyance path (FIG. 26) formed between the
fixed guide 122 and the movable guide 966 and smoothly guided to
between pinch holders 209 and platen boards 502 by a thin plate
member 207. The sheet 101 is then conveyed to the recording station
2.
On the other hand, the M- and S-size roll sheets 102 and 103 are
independently or simultaneously controlled by the coupling
mechanisms (FIGS. 23A and 23B) described previously. Accordingly,
it is possible to independently or simultaneously feed the M- and
S-size roll sheets 102 and 103. The sheets 102 and 103 fed from the
M- and S-size roll sheets 102 and 103 are conveyed along the
conveyance path (FIG. 26) formed between the fixed guide 121 and
the movable guide 968 and smoothly guided to between the pinch
holders 209 and the platen boards 502 by a conveyance guide 982.
The sheets 102 and 103 are then conveyed to the recording station
2.
Sensors S1, S2, and S3 are arranged in these conveyance paths and
detect the leading edges of the sheets 101, 102, and 103. The pinch
holders 209 can be rotated a predetermined angle by a guide bar
208, and a driving pinch roller 507 is rotatably supported by the
end portion of each pinch holder 209. By rotating the pinch holders
209 the driving pinch rollers 507 can be brought into contact with
and separated from the platen roller 501.
An image recording operation of the recording station 2 will be
described below with reference to FIG. 22. In the following
explanation, only an operation of recording a desired image on the
sheet 101 fed from the L-size roll sheet 101 will be described as
an example, and image recording operations for the other sheets 102
and 103 will be omitted.
The sheet 101 conveyed to the recording station 2 is nipped between
the platen roller 501 and the driving pinch rollers 507 and
conveyed to an image recording area.
In the image recording area, a platen unit 5 is evacuated to a
negative pressure by suction means 504. Consequently, the air is
drawn by suction from a large number of holes 502b (FIG. 26) formed
in the platen boards 502. These holes 502b are formed on the
downstream side of the sheet conveyance direction T.
The sheet 101 pushed out by the platen roller 501 and the driving
pinch rollers 507 is uniformly drawn to the platen boards 502 by
suction. Consequently, the sheet 101 slides on the platen boards
502 as it is kept flat.
A carriage unit 4 (FIGS. 21 and 22) having an image recording unit
401 capable of ejecting ink components of four colors {black (K),
cyan (C), magenta (M), and yellow (Y)} reciprocates in directions
indicated by the arrows in FIG. 21 along linear guides 203 and 204.
As a consequence, a desired image is recorded on the sheet 101.
That is, each color ink is supplied from an ink cartridge 4a
containing the ink to the image recording unit 401 via an ink tank
4b, forming a desired image on the sheet 101.
When the image recording as above is completed, the recorded sheet
101 is delivered to the processing station (not shown) by a pair of
paper delivery rollers 206. The sheet 101 is cut into a desired
size by a cutter 205 (FIG. 22). Note that the paper delivery
rollers 206 are a driving roller 206a to be pressed against the
non-recorded surface of a sheet and a driven roller 206b to be
pressed against the recorded surface of the sheet. The paper
delivery timing can be controlled by driving the driving roller
206a by a paper delivery motor 984 (FIG. 22).
Similar image recording is performed for the sheets 102 and 103 set
on the rear side. The sheets 102 and 103 are then cut into
respective desired sizes by the cutter 205 and delivered by the
paper delivery rollers 206.
As shown in FIGS. 27A and 27B, when the sheets 102 and 103 set on
the rear side are to be conveyed to the recording station 2, the
conveyance guide 982 for guiding these sheets 102 and 103 is
preferably arranged in a position (FIG. 28B) outside the conveyance
path so that the conveyance guide 982 can smoothly guide the sheets
fed from the roll sheets 100, 102, 102, and 103 different in the
size.
In the above embodiment, the L-, M-, and S-size roll sheets 101,
102, and 103 are set as shown in FIGS. 21 and 28B. However, the
present invention is not limited to this embodiment. For example,
the roll sheets 100, 101, 102, and 103 can also be set as
illustrated in FIG. 28A or 28C.
To set the LL-size roll sheets 100 on both the front and rear sides
as shown in FIG. 28A, the flange 100a is fitted on the sleeve 902a
of the front paper feed roller 902 and the other flange 100a is
placed on the step portion 902b (FIG. 20). As a result, the LL-size
roll sheet 100 is set on the front side. Also, the flange 10a is
fitted on the sleeve 912a of the rear paper feed roller 912 and the
other flange 100a is placed on the step portion 924b (FIG. 20) of
the rear paper feed roller 924. Consequently, the LL-size roll
sheet 100 is set on the rear side.
FIG. 28C shows an arrangement in which the LL- or L-size roll sheet
100 or 101 is set on the front side and three S-size roll sheets
103 are set on the rear side.
As has been described above, this embodiment can provide an image
forming apparatus in which the roll sheets 100, 101, 102, and 103
of arbitrary sizes can be set in arbitrary positions in accordance
with the use condition and the objective of use.
After the image-recorded portion is cut by the cutter 205, each
sheet is rewound a predetermined amount to the corresponding sheet
roll by the sensor S. FIG. 30 shows a standby state in which the
sheets 101 and 102 are rewound a predetermined amount to the sheet
rolls 101 and 102.
As can be apparent from this standby state, the sheets 101 and 102
are rewound such that the leading edges P1 and P2 of the sheets are
positioned between the pinch holder 209 and the paper feed roller
902 and between the pinch holder 209 and the paper feed roller 918,
respectively.
In this standby state, since the sheets 101 and 102 are kept in a
state in which the recorded surfaces are curved outward, the sheets
101 and 102 in the standby state are curled outward. In the next
image recording, the sheets 101 and 102 are fed from the sheet
rolls 101 and 102 to the platen boards 502 in the outwardly curled
state. The image-recorded surfaces of the sheets 101 and 102 are
properly drawn to the platen boards 502 by suction without floating
from the platen boards 502. Since the sheets 101 and 102 are wound
on the sheet rolls 101 and 102 such that the non-recorded surfaces
of the sheets 101 and 102 face outward, the sheets 101 and 102
conveyed from the sheet rolls 101 and 102 to the platen rollers 502
are curled in a direction to facilitate tight contact with the
platen surfaces.
In the first and second embodiments, it is preferable that the
sheets 101 and 102 be rewound on the sheet rolls 101 and 102 to
form slack portions N1 and N2, as shown in FIG. 31. In the above
standby state, curling of the sheets 101 and 102 positioned on the
paper feed rollers 902 and 918 can be moderated. In the next image
recording, this improves tight contact of the sheets 101 and 102
with the platen boards 502.
Additional advantages and modifications will readily occur to those
skilled in the art. Therefore, the invention in its broader aspects
is not limited to the specific details, and representative devices
shown and described herein. Accordingly, various modifications may
be made without departing from the spirit or scope of the general
inventive concept as defined by the appended claims and their
equivalents.
* * * * *